Sound beacon



P 28, 1955 w. A. MYERS ETAL 3,209,314

SOUND BEACON Filed Aug. 9, 1944 2 Sheets-Sheet l wCO INVENTORS WILLIAMA. MYERS BYVAUGHN G. McKENNEY ATTORNEYS Sept- 1965 w. A. MYERS ETALSOUND BEACON 2 Sheets-Sheet 2 Filed Aug. 9, 1944 United States Patent3,209,314 SOUND BEACON William A. Myers and Vaughn G. McKenney, SanDiego,

Calif., assignors to the United States of America as represented by theSecretary of the Navy Filed Aug. 9, 1944, Ser. No. 548,738 1 Claim. (Cl.340-5) systems are put is the detection of submarines and otherunderwater bodies, such as torpedoes and mines. As such systems havebecome more and more efficient, it has been found that there is greatneed for means and methods for defending against such detection, and itis one of the primary objects of the present invention to provide adevice which, when placed in the water, will confuse and interfere withthe information obtained by the echo-ranging and/ or listening gear onhostile craft.

Another object of the invention is a sound producing beacon designed foruse as a practice target for training operators in the use ofecho-ranging or listening equipment.

A further object is a sound producing device for defense againstsonic-torpedo or submarine attacks, which device may be thrown overboardor towed behind a vessel.

In furtherance of the first object, i.e. the confusion of craftattacking a submarine, the device, in its preferred form, consists of ahollow cylinder containing a power source, an oscillator and anamplifier. It is further provided with a transducer for converting theelectrical energy into sound energy and a buoyancy control forsupporting the whole unit at a desired depth in the water. It may becarried either within the submarine for ejection from a fiare, torpedoor specially constructed tube, or on the outside of the submarine forrelease from Within. When ejected or released, the device beginsoperation, sending out sound waves which are received by the hostilevessel. One or more of the beacons may be placed in the water by thesubmarine, and, if they are properly positioned with respect to theattacking vessel, will confuse or sufficiently interfere with theoperation of the sound equipment on the attacking vessel as to makedetection and/or identification of the submarine very diflicult orimpossible. It is obvious that the loss of contact for even a fewminutes during the critical attack period offers the submarine a badlyneeded opportunity for taking evasive or escape action. Additionally, itis quite possible that in the resulting confusion aboard the attackingvessel, the attack may be made upon the sound beacon rather than on thesubmarine.

If the beacon is to be used as a training target, it is provided withessentially the same elements. When it is placed in the water, trainingships are guided to its position by the emitted sounds, and may conductsimulated attacks upon it. In this case, it may be desirable tosubstitute a buoy for the buoyancy control means, in order to suspend itat a predetermined depth and to facilitate retrieving the device whenthe exercises are completed.

When used as a defense against sonic torpedoes or submarine attacks, itmay simply be thrown overboard or towed behind the ship to guide thesubmarine or torpedo to a position remote from the ship.

In the drawings:

FIG. 1 is a side elevation, cut away for clarity, of one embodiment ofthe invention.

3,209,314 Patented Sept. 28, 1965 FIG. 2 is an elevation, partially insection, showing one form of transducer and the method of attaching itto the embodiment of the invention shown in FIG. 1.

FIG. 3 is a schematic diagram of an electrical circuit designed for usewith the invention.

If size and space considerations are ignored, a preferred form of theinvention consists of means for producing high intensity sound at allfrequencies likely to be utilized in listening or echo-ranging. Thismight require that the entire range from 0 to kc. (kilocycles persecond) be covered, as the device would obviously serve no usefulpurpose unless the frequency range of the hostile sound gear waseffectively blanketed. Since an opposing vessel might be equipped withseveral sonic listening and supersonic echo-ranging equipments(operating simultaneously at several frequencies), the device wouldnecessarily be very large in order to incorporate a power supply andgenerating equipment suflicient to cover the entire range.

These requirements are not difiicult to meet when the device is to beused for training purposes or is adapted to be thrown from the deck of asurface ship. In these cases, a very large unit, or a plurality of unitsmay well be'used.

But since its most useful function is performed in conjunction withsubmarine escape or evasive maneuvers and because it is undesirable toattach even small mechanisms to the outer hull of undersea craft, spacelimitations become exceedingly important. It is thus obvious that adevice is desired which may be conveniently stowed in a small space andwhich can be ejected from existing outlets in submarine hulls. Theseopenings consist of the torpedo and the signal flare tubes; and the mostconvenient of these is the signal flare tube. In conventionalsubmarines, this tube will eject a cylinder not larger than 3" indiameter and 33" long.

With this space limitation, it is not feasible to attempt constructionof a device which will cover the entire frequency range mentioned above.However, it has been found that the effectiveness of echo-ranging andlistening gear can be substantially reduced if extraneous soundscovering a frequency range i2-5 kc. from the mean operating frequency ofthe gear are present, assuming, of course, that such sounds are producedat sufiiciently high intensities. It has also been found that thisinterference or masking is most easily accomplished when this sound isfrequency modulated, as, for example, by sweeping this range offrequencies in saw-tooth fashion. Thus, if it be supposed that a hostileship is echo-ranging at a mean frequency of 24 kc., it is found that atreasonable ranges and bearings, the present invention can effectivelymask or so confuse the gears indicating mechanism that very littlevaluable information is obtained if it produces sound varying infrequency from 20.5-27.5 kc. at a saw-tooth frequency of about 4 c.p.s.It has further been found that such a device may be constructed tooperate from 10-30 minutes even though its physical size is limited to acylinder 3" in diameter and 33" long, as required above.

A device of this size and type is shown in FIG. 1. It is to be clearlyunderstood that although this form of the invention will be describedherein, it may be embodied in a variety of forms, which are determinedby the con siderations discussed above. In general, it comprises awater-tight container, generally designated 1. This container, which mayconveniently be formed of A aluminum, comprises a tube 2, one end ofwhich is countersunk to receive an end plate 3. The protruding end ofthe tube is crimped over a neoprene or rubber gasket 4 to provide awater tight fit, as best shown in FIG. 1. A bracket 5 is mounted on theend plate 3 by means of spacers 6 and bolts 7 and supports a buoyancycontrol device, generally designated 8. This control may be of anyconventional type, but the type disclosed in a patent applicationentitled, Buoyancy Control Device, Serial No. 533, 895, filed May 3,1944, by Raymond D. Atchley now Patent No. 2,793,589, has been found tobe most satisfactory and is illustrated in FIG. 1. This mechanism is onewhich will maintain the unit at a substantially fixed and predeterminedlevel for a given period. This period is dependent upon the amount ofactive gas producing element contained in the buoyancy mechanism, whichneed only be sulficient to support the device at the required leveluntil the energy available for operating the electronic equipment isexhausted. After the period has elapsed, the resulting negative buoyancycauses the unit to sink to the bottom of the ocean.

A transducer, generally designated 9, of any conventional type, such asmagnetostrictive, piezoelectric or electro-dynamic, is secured to theopposite end of the container 1. Any convenient means of securing thetransducer may be used, but in FIG. 2, the end of the transducer isprovided with a conventional female bayonet fitting adapted to interlockwith several male bayonet studs 11 on the inside of tube 2. The outerdiameter of the female fitting 10 is the same as the inner diameter ofthe tube 2 and it is provided with an external offset, as at 12. Arubber gasket 13 is placed around this offset and is engaged by the endof the tube 2 to provide a watertight seal when the two are lockedtogether.

The electronic gear comprising the power supply, oscillator, andamplifier are all conveniently located within tube 2 and connected tothe transducer 9 by leads extending through the fitting 10.

The particular circuit used to supply power to the transducer isnaturally determined by the type of output signal desired, which lattermay be a fixed signal or one which is amplitude and/or frequencymodulated. The main requirement for its production is that the necessarycircuit fit into the physical space provided.

The circuit illustrated in FIG. 3 is one which produces a frequencymodulated saw-tooth signal and, with the circuit values given, has beenfound to satisfy both space and operational requirements. It will bedescribed in detail, but it is to be clearly understood that the valuesgiven, and the particular arrangement used, are illustrative only; thereare other arrangements which will perform equally well.

It comprises, in general, four elements: a power supply, a mainoscillator, a sweeper oscillator and an output stage.

The power supply consists of a battery B, which is conveniently a 6 voltWillard N-T-6 (Navy Type CWB 19046), a 180 cycle vibrator and a smallvibrator power transformer, T isolated by means of condenser C Thiscircuit delivers approximately 90 ma. at 330 volts. The main oscillator,tubes V V is a conventional multivibrator whose frequency is determinedby the value of condensers C C and resistors R R R It suppliesessentially a square wave, whose corners are rounded off by the heavyload drawn by the output stage.

The sweeper oscillator, tube V is a gas tube supplying a saw-toothoutput. Grid current from the main oscillator tubes V V chargescondenser C until the voltage across tube V drops and fires it, causingthe condenser to discharge. The cathode of tube V thus has a saw-toothvoltage pattern, the frequency of which is determined by the values ofcondenser C and resistors R R R and causes the frequency of the mainoscillator V V to vary in a similar manner. The firing voltage of tube Vis determined by the voltage divider comprising resistors R R andresistor R serves as a current limiting resistor, protecting the tube.

The resistors R R R (the latter of which are arranged to be variedsimultaneously) are made variable so that any one of a number offrequency bands can be chosen for operation and, if desired, may be soarranged 4- that this setting may be made by a switch mounted externallyof the unit.

The main oscillator V V is coupled, through resistors R R and condensersC C to the output stage V V In FIG. 3, this is seen to comprise apush-pull amplifier, although one or more power amplifiers, connected inparallel, might be used. It will be noted that the plate resistors R Rassociated with the main oscillator, are by-passed by voltage dividerscomposed of resistors R R and R R If the output stage is found not toload the main oscillator to an undesirable extent, these voltagedividers may be omitted and the coupling condensers C C may be tieddirectly to the plates of tubes V V The plates of the output tubes V Vare supplied through center tapped choke L while the grid bias andscreen voltage are supplied through resistors R R and R respectively.Power is supplied to the transducer terminals through a resonating chokeL For most efficient operation, choke L should be several times largerthan choke L A switch S is provided in the battery circuit to put thedevice in operation. Any convenient type may be used, as discussedelsewhere herein, depending upon the time at which it is desired tobegin operation. Filament voltage for each tube is supplied fromarrow-headed terminals F, F.

If the values given for the various elements on FIG. 3 are used, andvariable resistors R R are set at 2.0 niegohrns, it is possible to applyto the transducer terminals a saw-tooth signal varying in frequency from20.5 to 27.5 kc. at a sweep rate of about 4 cycles per second. This,however, may be altered as desired by varying resistors R and R R Withthe 20 Y-cut crystal transducer described herein, successful operationfor a period from 20 to 30 minutes is possible.

In the event that it is desirable to vary the frequency of the mainoscillator in some other manner, conventional circuits may be used. Forexample, two or more multivibrators may be used to separately drive asimilar number of output tubes. The multivibrators may be made tooperate over the same or different frequency ranges and may be swept atthe same or different rates.

The Willard-Navy type battery illustrated may be replaced by any otherconvenient power supply, as for example, one of recent development,called a sea cell, which utilizes sea water as an electrolyte. In thiscase, the electrodes are positioned to be in contact with the water andsuitable leads are provided to supply the circuit elements in thewater-tight tube.

As has been stated above, any type of transducer might be used with theinvention. However, since the complete device is expendable and becauseweight is an important factor, the transducer illustrated in FIG. 2 hasproven very effective. The unit, generally designated 9, is housed in athin metal cylindrical container 14 which, in practice, is simply a canof the type used in canning fruits and vegetables commercially. Thecontainer has a bottom 15 fitted with a threaded sleeve to receive afilling plug 16. The crystal motor comprises a stack of 20 standard NavyY-cut Rochelle salt crystals 21 connected in parallel, positioned andinsulated by corprene spacers 22. The motor is positioned by means ofcircular corprene washers 23 (of a diameter equal to the inner diameterof container 14), glued to its ends. These washers are properlyperforated to receive the filling plug 16 and a pair of water tightgrommets 24, positioned in the lid 25, through which the leads 26 arebrought for connection to the transducer terminals on the amplifier. Thelid 25 is clamped to the container in the conventional manner and thewhole unit is filled with castor oil.

The transducer is mounted on the female portion 10 of the bayonetfitting by providing the latter with a thin, circular flange 27 which iscrimped over a gasket 28 to form a water tight seal around the edge ofthe lid 25. The transducer with the bayonet fitting is thus adapted tobe locked into the lower end of tube 2 as described above.

In use, the complete device is ejected from the signal flare tube of thesubmarine. Immediately on reaching the water, the buoyancy mechanismtakes control and brings the unit to rest at its pre-set level, asoutlined in the patent application identified above, the buoyancycontrol mechanism being uppermost and the transducer being lowermostwhereby the gas escaping from the buoyancy mechanism will not pass bythe transducer and cause blocking of the signals therefrom or otherwiseaffect said signals.

The electrical circuit may be arranged to begin operation at any one ofseveral times. As shown in FIG. 3, it is controlled by switch S, whichmay be arranged to be closed manually before the unit is placed in theflare tube, automatically upon ejection from the flare tube, after acertain delay period (as controlled by conventional delay mechanisms orthe dissolution of soluble plugs), or at a predetermined depth (ascontrolled by a pressureactuated mechanism). It will continue to operateuntil the available energy of the batteries has been used, and will sinkto the bottom when the active element in the buoyancy control mechanismis depleted (as explained in the patent application identified above).

One or more of the units may be used. One unit may, under favorablecircumstances, be sufficient, particularly if it is positioned close tothe attacking ship and between that vessel and the submarine. At othertimes, it may be desired to eject several devices to produce furtherconfusion or to create an effective sound mask between the two vessels.

Obviously, when only one unit is ejected, only sound of a predeterminedrange or ranges of frequencies will be emitted. Depending upon theelectronic construction, this may be sound of a constant frequency, aplurality of range of frequencies, or a swept range of frequencies, asproduced by the circuit shown in FIG. 3. If a plurality of oscillatorsor separate units are used, several ranges in the sonic and/ orsuper-sonic spectra may be effectively covered by one unit.

The invention may also be utilized in connection with control mechanismsof the type used in torpedoes If provided with a propeller, rudder,diving vanes and a directional gyro control, it may be made to traveltoward a hostile ship; or, directed toward the hostile ship, as

a source of sound, in accordance with principles utilized in theconstruction of sonic torpedoes. This construction has the advantage ofbringing the beacon closer to the hostile sound gear, efiectivelyincreasing the observed intensity of its signals, compared to those ofthe more remote submarine.

Having described our invention, we claim:

An underwater sound beacon adapted to be launched from a water bornebody comprising a signal generating means producing a continuous signal,automatic means for varying the frequency of said signal over apredetermined frequency range of about 20.5 to 27.5 kilocycles persecond in a saw-tooth fashion, control means for selecting the frequencyrange of operation of said signal generating means, amplifier means forsaid signal, a transducer coupled to said amplifier means and operativeto transmit said signal directly into a Water medium at a highintensity, and gas operated buoyancy means for supporting said beacon ata predetermined level underwater during the life of operation of thesound beacon whereby signals transmitted into the water are operative tointerfere with hostile sonar operations.

References Cited by the Examiner UNITED STATES PATENTS 952,452 3/10 Leon177-3863 X 1,440,596 1/23 Hammond 177-38610 X 1,466,284 8/23 Harlow340-6 1,610,779 12/26 Hewett 340-2 1,709,890 4/29 Wilckens 177-3865 X1,892,431 12/32 Hammond 177-386.1 X 2,082,317 6/37- Barber 340-16 X2,268,643 1/42 Crosby 340-16 X 2,353,360 7/44 Ronning 340-4 X 2,361,17710/44 Chilowsky 340-2 2,397,107 3/46 Hammond 340-2 X 2,433,361 12/47Harrison 340-3 2,465,993 4/59 Beechlyn 340-2 X 2,536,771 11/51 Rost340-3 FOREIGN PATENTS 334,102 7/ 15 Germany.

LEWIS H. MYERS, Primary Examiner.

HILLET MARANS, NORMAN H. EVANS, WILLIAM G. WILES, Examiners.

